Aero frames

dennisn

Just a subject for speculation, nothing more. I would be willing to bet that given two
very distinct frames, a lugged steel one and an all out carbon fiber one, that when
only frame and fork are put into a wind tunnel the steel bike would be the more aero.
I base this theory on the fact that steel frames and forks have much smaller tube
diameters and therefore less surface area for the air to have to deal with. This may
seem a bit simplistic but I have never heard of any compairision studies on this subject.
Could it be??? Steel is more aero???

Dennis Noward

fossyant

Possibly, but there is a big human sat on the top of it !!!

simbil1

It depends on the cross sectional area presented to the direction of movement and the drag coefficient (function of shape and smoothness).
The area will be smaller with a steel frame compared to say an oversized alu frame and probably smaller than a carbon frame too.
The coefficient of drag is 0.1 for a smooth sphere but as low as 0.005 for a plate shape moving sideways through the air.
So, for a non-aero shaped carbon frame, it would indeed be less aero than a skinny steel frame.
But for an aero shaped carbon frame, I'd expect the coefficient of drag to be a fair bit lower which would tip the balance to the carbon frame being more aero.
I wonder if aero manufacturers publish the coefficient of drag for their products or just talk a load of marketing BS

gkerr4

hmm - depends on the frames i think

or example the 'Look' frames - the ones with a lugged construction - are carbon but aren't oversize tubing

plus a carbon frame can be designed and crafted to give an aerodynamic advantage - where steel tubes are just narower .

aracer

Aero is nowhere near as simple as that. There's a good chance the lugs would more than make up for the smaller tubes in terms of aero drag - or even the possibility that the smaller tubes aren't actually beneficial when you consider the whole system including rider, wheels, bottles etc.

dennisn

The reason I brought this subject up was because I was riding in some tour, somewhere
and a younger rider, much younger, early twenties, came up alongside of me and
asked me what kind of fork I had on my bike(chrome steel). He said he had never seen
a fork so "thin and skinny" before. I told him it was a new wonder material called steel.
He laughed and said he had read about steel in the history books. Ah, to be young
again. And he had a sense of humor. But he was serious about the thin fork.

Dennis Noward

aracer

Well if you're talking forks, then it was probably skinny front to back, but not necessarily more skinny across the width, so likely to be less aero than a typical carbon fork (and a lot less aero than the fairly common bladed carbon fork).